Automatic telegraph keying head



May 11, 1932. g. KUNG ET AL 1,858,511

AUTOMATIC TELEGRAPH KEYING HEAD Filed May 22, 1951 6 Sheets-Sheet l Wvm' TTORNE May 17, 1932. i F KUNG ET AL 1,858,511

AUTOMATIC TELEGRAPH KEYING HEAD .Filed May 22, 1931 A6 VShee'lZS-Shet 2I -p INVENTOR5 May l`7, .1932. F. KuNc ET AL.

AUTOMATIC TELEGRAPH KEYING HEAD I Filed May 22, 1931 6 sheets-sheet 3 ImrAoRNEYs May n17, 1932. F, KUNC E1- ALy 1,858,511

AUTOHTIC TELEGRAPH KEYING HEAD Filed May 22, 1931 6 Sheets-Sheet 4 QL l.

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INVENTRb Mm c;

' ORNE@ May 17, 1932. n F, KUNC ET AL 1,858,511

ATOIIATLC TELEGRA-PH KEYING HEAD iled' Hay 22. 1931 6 Sheets-Sheet 5NIV, un., o

I 'i llllll nmlu www Imi-ilu i o dm- TToRNEYs,

May 17, 1932. F. KuNc E-r Al. 1,838,511

AUTQIIATIG TELEGRAPH KEYING HEAD Filed lay 22, 1931 6 Sheets-'Sheet 6 o"Hill BY s. mi y /l M ATToRNL-:Y5

m/ Y ENToR;

Patented May 17, 1932 Unirse sT-A'ijas PATENT vcitric-121 FRANK KUNG, OFNW ROCHELLE, .AND ERNEST KNOPIRA OF BRONX, NEW YORK, ASFkv SIGNOBS TO H.0. BOEHME, INC., OF NEW YORK, 1\l'.` Y., A CORPORATION OF NFN' YORK4AU'roiiiaTic TELEGRAPH Karinel HEAD' Application ledMay 22, 1931.Serial'No; 539,334.

'f rela-tein particular to the mechanical construction of such keys bywhich we areenabled to operatethe key at a much higher speed than ispossible, so far as we are aware, with the keys at present in use.

i The present day automaticV keys either make or break the contact` ordol both, by spring power, and only the mechanism which controls thesprings is positively operated. As soon as a certain operating speed isattained by such a. key, natural oscillations are set up in the contactmechanism, due to the elasticity of the springs and the masses Vwhichthey control, which oscillations seriously interfere withthe pi'opertiming of the contacts, with respect to their make and break, so thatfor instance Morse dots and dashes become very irregular andindistinguishable from one another.

In our improved automatic keying mechanisin these difliculties areovercome by positively gearing and operating at all times all elementsof the mechanism which are directly concerned in. the movement of theContact l arm. so that this arm is at all times only` positively moved,whereby the operating speed ot the key can be increased to several timesthe speed of the keys at present in practical use for line or radiotransmission. A Our invention is illustrated in the accompanyingdra-Wings in which; Y

Fig. l represents a top plan view of the keying head; Y v

Fig. 2 represents a front view of the keying head with parts brokenawayto showt7 the lcontact mechanism 1 Fig. 2a represents a detail ingreatly enlarged. partly vertical sectional view, of the toggle jointinFig. 2, for holding-the con- Fig. 4-represents a rear view of thekeyingv head, with parts broken away to show the gear drive;

Fig. 5 representsaplanview of the-selector lever gear housing in largerscale;

Fig. 6 represents a vertical section ofthe saine housing on the samescale taken on the line 6 6 of Fig. 8; i

Fig. 7 represents*axliorizontal section of the lever housing through thelever pivots on s Fig. 8 represents a front viewo the-lever housing inthe same scale with front cover removed, showing the selector pin leversin a position in which both selector pins are drawn furthest apart, `pins receding from,

pin m advancing into a hole in drum 20, con'- tact arm on lower(spacing) contact;

y Fig. 9 represents the same view as Fig. 8, `with the driving crank pinl for the selector levers advanced over Fig. 8 one-quarter turn toposition II, showing the marking selector pin'madvanced completely intova hole of the selector drum, contact arms still down,

spacing selectorpin withdrawn `from selector drum hole, contact armabout to be lifted from spacing contact S; Y y Fig. 10 represents thesame View as Fig. 8 with crank pin advanced another one-quarter turn toposition III, both selector pins iii transverse alignment, contact-armhas beenV moved up to marking contact M, pin m about to withdraw from,pin s advancing into drum Fig. 11 represents the same view as Fig. 8.

With'crank pin'advanced another one-quarter turnto positionlV, spacingselector pin s advanced completelyfinto selector drum hole,

pin my completely withdrawn, contact armv still Yup, ready' t Fig. 12represents a greatly enlargedhorizontal section through the lowercontact block 72 'of Fig.V 2'; v j,

Fig. 13 represents a greatly enlarged frago return to spacing contact 195 menta-ry vertical section through the contact block tip on the line13-13 Fig. 12;

Fig. 14 represents a greatly enlarged fragmentary detail of the tapedrive seen in plan in Fig. 1;

Fig. 15 represents an exploded perspective view of the contact lever andits interlink- -ing lever shown in Figs. 8 to 11;

Fig. 16 represents a front view of the selector lever housing in reducedscale, showing the eccentric mechanism for throwing lector pins withrelation to each other and with the selector drum, v

' Fig. `19 showing the spacing pin s ing from, and the marking pin madvancing through a hole in the tape, into a selector drum hole(corresponding to position Fig. 8 i i' i )Fig 2O showing the marking pinm' entirely advanced, spacing pin s entirely withdrawn, rotation ofselector drum about to carry pin fmy to left to throw contact lever up,(corresponding to position Fig. 9),

Fig. 21 Vshowing the spacing pins advancing, marking pin m retracting(corresponding to Fig. 10),' Y

5 Fig. 22 showing the spacing pin s entirely advanced, marking pin mentirely with# drawn, rotation of selector drum about to carry in s toleft, to throw contact lever down corresponding to Fig. 11),

'i Fig. 23 showing the relative' position of selector pinsA as in Fig.22, but prevented from entering drum holesfwhen tape has no-Aperforations Fig. 24 represents a fragment of a perforated transmittingtape, to show spacing of telegraph code symbols, and

. telegraph code.

Fig.25 represents a similar fragment of a receiving tape on which thetransmitted symbols are recorded in dots and dashes of the Discussingfirst the-underlying principle of the conventional perforated tapecontrol for automatic keyingreference,is made to Figs. 24 and 25 and tothe circuit diagram shown in Fig. 16., In this latter ligure for examplea direct current source D. C.` is employed at the transmitter end of thesystem, shown in that figure, across which source a resista-nce fr isconnected which is tapped in the center. One e'nd of At-his resistanceis connected A to the retractspacing contact S of the transmitter key,and the other end of the resistance is connected to the marking contactM of the key. The center of the resistance is connected to one terminalof the receiving coil at the distant receiver, the other end of thiscoil being connected to the contact A of the contact arm which operatesbetween the two contacts by the function of the key mechanism which willbe described later. If for instance the arm contact A is thrown onto thespacing contact S, a current flows from the center of the resistance,through vthe line, in the direction of the righthand arrow through thereceiver coil and through the other side of the line over contacts A, Sto the minus side of the source. If the arm contact A stands on thefmarking contact M, the current flows in the direction of the left handarrow through the distant receiver coil. Thus, according to the positionof the key contact arm, the distant receiving coil, by means well knownin the art and not shown here, causes the throw of an inked pen p to oneor the other side of a moving receiving tape, of the character shown inFig. 25.

The time for which the pen remains on one or the other side of the tapedepends upon the duration of the contacts between contact A and S or M.When contact is made for a certain len th of time at M, for instance oneof the mar (ings a2 heavy lined in Fig. 25 produced on the receivingtape which represents a code dash. )Vlien cont-act is made at S, the penswings to the other side of the tape and now the first of the spacingsymbols b2 is produced which spaces the iirst code dash a2 from thesecond following'dash a2. Vhen marking contacts of shorter duration areVmade, code dots such as c in Fig. 25, followed by spaces, the same as52will bev produced.

-If the contact arm remains a comparatively long time on the' spacingContact, long spaces, such as between words, shown at b1 in Fig. 25

.are produced'.

The correspondingly perforated tape shown in Fig. 24 when fed throughthe transinitter keying head according to the present invention, permitstwo suitably disposed selector pins, one for each longitudinal row ofholes, to enter the perforations and a pin Vconveying drum in a mannerto be described presently, and while a pin remains in the perforationand in the drum, and the latter with tape continues to travel, the pinis taken along laterally a certain distance and by its tilting causesthe contact A of the key to move on one or the other contact and toproduce the signals referred to hereinabove.

`F or instance, a selector' pin entering the iiist marking hole f1.2 inFig. 24 would be taken to the left with the travelling tape and by themechanism to be described would closeI immediately the marking contactwhich remains closed (thereby producing the first dash a2 in Fig. 25)until the other selector -mounted the selector lever box 12 pinencounters the next spacing hole 2in Fig. 24, when the Contact arm isthrown at once onto the spacing contact to produce the first space b2 inFig. 25, which ends` when the marking pin encounters the second markinghole ca which throws the contactarm back onto the marking contact ofthe'key, and so forth. The two tape fragments in Figs. 24 and 25 areshown vertically above one another and the ti'acing produced by thereceiver pen p according to each particular transmitter tape perforationshown in Fig. 24, is shown immediately below in Fig.

lith this preliminary explanationin mind. the mechanical constructionand function of the keying head will now bedescribed.

The keying head consists of four'principal mechanisms: tie selector pinoperating lever mechanism shown in detail in Figs. 6 to 11; the drivinggear trains for the lever mechanism, shown in detail in Figs. 3 and 4;the contact lever mechanism, shown in Fig. 2; andY the tape releasemechanism shown in Figs. 2, G, 16, 17 and 18.

Referring first to the driving gear trains and to Figs. 1, 2, 3 and 4,the keying head comprises a main box 10 which contains the driving gearandwhich is mounted on a base plate 11, as shown more particularly inFig. 2. On the front of the main box 10 is' and adjacent to the latterthe contact box 13.

The driving gear in main box 10 comprises a driving shaft 14 whichprotrudes at the rear of the box as shownvin Fig. 3 carrying at itsouter end a saw tooth coupling 15 by which it is coupled to theconventional driving mechanism used in this type of'keyfnot shown).Through a train of step up gears 16 shaft 14 drives the main operatingshaft 17 which extends intothe selector lever box 12, and which will bereferred to later. Through another train of step down gears 18 shaft14drives the selector drum or tape drum shafty 19-on whichis mounted atthe front of box 10 the selector or tape drum 20 right above theselector lever box 12. This selector drum, shown more detailed in Fig.14, is provided with a gear 21 at the outside of box 10 which mesheswith a gear 22 integral with the star wheel roller 23, the pin teeth 24of which engagethe central row of perforations of the tape 26 shown inFig. 24, when the tape is laid around the lower portion of the tape drumperiphery as shown in Fig. 2. The pin teeth 24 run freely in a groove 27provided in the tape drum 20. By this last described gearing the tape ispositively driven with re- ".pect to the drum 20, so that theperforations in the two outer rows of the tape when present, will alwaysprecisely register with the two rows of selector pin ho`1es'28 and 29provided in drum 20; An idling roller 30 is pro vided on the other sideof drum 2O` by which are mounted in a frame the tape 26 is guided ontoand held on drum 20. The star wheel roller 23 and idling roller 30 arerespectively mounted on arms 31, 32, the upper ends of which tachedtothe front of main casing 10. They are held in the position shown inFig. 2 by means of a tension spring 34 shown in in dotted lines, therebypressing the star ywheel roller and the idling roller against the tapeand selector drum 20. The release of this mechanism for insertion orremoval of tape 26 will be described later. Arm 31 is provided with astripper 33, the end of which extends close to the roller 23, straddlingthe teeth of this roller are pivotally at-l rige.v

periphery of star wheelY v l 8o l as shown in Fig. 1, for the purpose ofprompt ly freeing the tape from the star wheel teeth and to facilitatethe smooth running off of the tape in the direction of the arrow shownin Fig. 2. From this gear drive, so far de# scribed, it will be observedthat the selector lever operating` shaft 17 all gear wheels run in ballbearingss'uch asl shown :at 35, and in order to facilitate the (Fig. 3)and the tape or selector drum20 and the tape feeding mounting of thegears, the twoigeartrains 16 drive shaft 14 36 which is inserted of gearbox 10 as shown in and 18 together with the main into the rear wallFigs. 3V and 4. Referring now to the selector pin operating mechanism,contained in lever box 12 this Vmechanism is constructed as follows.Referring to Figs. 6 to 11, and in particular to Fig. 8, 17 is the driveshaft for this mechanism, previously described as extendingV from mainbox 1() into selector levery box 12 as shown in F ig.6. In the lever box12 and mountedabove shaft 17 is a transverse pivotal shaft which has athin portion 38 ex- Yma tending through a guide bushing 39'bey0nd thefront of box 12, and which is" also pro'- vided with a thick portion 40journalled' in the rear wall of box 12. 41 of this shaft is eccentricfor reasons to be described later on. and the thin end 38 of'the shaftare shown in F 8 to 11 in end view. The eccentric portion 41 serves as-apivot for a rocking frame42 which has a forked lower end in which aguide block 43 which block engages a pintle 44 eccentricallydisposed atthe end Vof gear shaft 17 (see also Fig. 6).

driving Thus when shaft 11o ff The central portion f Theeccentricportion 41 is slidingly disposed i 17 revolves, rocking frame42 isrockedon eccentric '41 from one siderto the other, as-

suming successively shown in Fig. 8, then the inclined position anotherone-quarter turn again a central posithe central position afterone-quarter turn tion shown in Fig. 10, and after another one- Y an'inclined position shown in Y e 130 A quarter tif-,rn Fig. 11.

shown in Fig. 9, after Rockinglframe 42 has near its'pivot point twolateral extensions 45 and 46 which carry respectively the two transversepivot pins 47 and48. lBy these pivot pins the selector pin levers 49.and 50 respectivelylare attached to the rocking frame 42, forinstance asshown atithe left hand side of Fig. 8, means of a transverse slidingblock 51, `which can slide in the transverse slot 51a provided in eachframe.V These levers which have the shape of iframes, are guidedrespectively by guide blocks 52, 53. Guide block is `fixed-tio aninterlinking-lever 54, and guide block 53 to contact lever 55, whichlatter protrudcs through the wall of box 12, its outer end cooperatingwith contacts M and S. The shape of theseV two lastA mentioned levers isshown more clearly'in anexplodcd perspective view in Fig. 15. These twoguide blocks and levers are pivoted each on a separate axle 56, theaxles extending from the rear wall through box 12 (see also Fig. 6) onwhich axles theA levers can freely rock. The two levers are besidesinterlinked by means of a pin 5T which is located in a sliding block 58slidingly mounted inthe rear end of lever 55. These elements are veryclearly shown in Fig, 15. From this interlinking it becomes obvious thatwhen one lever is rocked clockwise the other will be rocked counter'clockwise, and vice versa. The guide blocks 52, 53 of these two levers,which, as was stated before, serve as longitudinal guides for therespective selector pin frames49 and 50, are set with respect to thelongitudinal axis .of their pertaining levers at an angle, as appearsfor instance from Figs. 8 and 15,'so that the two selector pin framesystand inclined towards one another. 'Assuming for themonient thatinterlinking lever 54 and contact lever 55 are held stationary androcking frame 42 is rocked' from one side to the other by main driveshaft 17, the two selectorV pin frames 49 and-.'alternately merely moveup and down longitudinally, so that their respective selector pins m ands which protrude from their upper free ends movebalternately into andoutof the hollow tape bridge 60 which is mounted .on top of gear box12.`For this purpose the top of the bridge, which closely follows thecontour of the tape or selector drum 20, is provided with slots 61 and62 respectively (see also Fig. 5).`

As shown for instance in Fig. 8, each of `the selector pins mand s islongitudinally Guided in its pertaining frame and is provided with acollar 63 which is located inside of theframe. The inner end of each pinis guided in a hole 64 provided in the pertain- 'ing frame guide block.Between the guide blockand the collar is arranged a spring65 whichtendsto keep the collar in contact with the inner upper end of the frame, andthereby tends to maintain the pin pushed` out of the frame as far aspossible. Thus, when such avselector frame is retracted by the rockingmotion of rocking frame 42 its selector pin is retracted with it againstthe tension of its spring. The description of this frame constructionhas been made only with respect to frame 50, it is the same with respectto the other frame 49.

As will also be noted from Figs. 8 to 11 and also from'Fig. 6, the twoselector frames 49 and 50 are pivotally attached to rocking frame 42 atopposite sides, frame 49 being attached to the rear of frame 42 in Fig.8, and

'marking pin m is located to the rear, and the spacing pin s at thefront (see alsoFig. 5). The selector drum 20, around the lower portionof which the tape runs, and with the A holes 28 and 29 of which theperforations in the tape-if present-register, ashas been describedhereinbefore, is positively geared and timed with relation to therocking motion of frame 42, so that for instance when the spacing pin min Fig. 8 commences to protrude through its slot in the tape bridge l60,a hole 29, shown in dotted li-nesin Fig. 8,

has arrived in line to permit the marking pin m to enter. The row ofmarking holes'A 29 are drilled into drum 20 at an angle to the drumradius so that' when the marking pin m has arrived near, or at thebottom of a hole. as shown in Figs. 9 and 20, it will come in contactwith the wallof the hole at the right hand side, so that when drum 20continues revolving in the direction indicated by the ar-` row in Figs.8 to l1 and Fig. 20, marking pin m will be taken along to the left intothe position shown in Fig. 10. In other words,

guide frame 49 of marking pin m, aside from l performing a longitudinalmotion due to the operation of rocking frame 42, Twill also swing to theleft on its pivot stud 56 from the position in which it is shown in Fig.8 to the position in which it is shown inV Fig. 10. Since the guideblock 52 of frame 49 is .rigidly attached to -interlinking lever 54,this leverk is rocked counter clockwise from the position shown 1n Fig.8 into the .position shown iny Fig. 10 which, due to the interlinking ofleven 1 V ers 54 and 55, will cause contact vleVl 55 to rock clockwiseto the Vsame langular vextent from the position shown in Fig. 8 lto thepoy sition shown in Fig. 10; In other words, `whereas in'Fig. 8 theouter end of contact lever 55 which protrudes to the left beyond casing12 is in'contact'with the spacing lcontact S, it has been'thrown by the'aforemenida. .i

tioned rocking motion upward into the posiy .y

tion shown lin Fig. 10 :where it'makes Contactv with the marking contactof the key. The detailed construction of these contacts will be referredto shortly hereinafter. While the marking pin m, has just beendescribed, enters one of the marking holes 29 of drum 20, frame 50 ofspacing pin s moves longitudinally downwardly into the position shown inFig. 9, whereby ith-as `retracted its pin s from the spacing hole 28 ofdrum 20 in which it is shown in Fig. 8, so that the tip of the pin isbelow the surface of tape bridge 60. This permits the aforedescribedrocking of frame 49 by drum 20 to the left; When contact arm 55 swingsupwardly from the position in Fig. 8 to the position in Fig. (l0, frame50 ofthe spacing pin s rocks with arm 55 clockwise into the positionshown in Fig. l0 in which the tips of the two pins m and s are shown intransverse alignment, which is the closest approach of the pin tipstoone another, whereas in Fig. 8 they are shown furthest apart. In Fig. 8with the contact arm on the spacing contact S, and the selector pins mand s are always drawn furthest apart. and are in spacing position,whereas in Fig. l0, wthcontact arm 55 .on the marking contact, `the twoselector pins m and s are in marking position. In 9 the pins, so far asthe tilting ofthe two frames 49 and 5() is concerned, remain Still inspacing position in which they are `shown in Fig. 8. and theirpertaining selector frame only performs a longitudinal motion to eitherwithdraw its pertaining pin from aihole in drum 20, or to advance itspin into it, as the case may be. Similarly in Fig. 1l the two pins m ands, together with their pertaining frames remain in the same markingposition shown in Fig. 10, and in the position 1l, the frames onlyperform longitudinal motion to withdraw a pin from, respectively advanceit into one of the holes.

vWhile marking pin m has been tilted by drum 20 from the position shownin Fig. 9 into the position shown in Fig. 10 to cause arm 55 to make amarking contact, rocking frame 42 has gradually arrived in the positionshown in Fig. l0, in which the marking pin m is still in its markinghole, but in which the spacing pin s has been in the meantime partwayadvanced into a spacing hole which is transversely in alignment with themarking hole in which the pin m is located at the time. This has beenmade possible by the tilting of pin s from the position shown in Fig. 9into position shown in Fig. l0, in which it mee-ts the hole as it were.Itwill be noted from Figs. 8 to llas well as from Figs. 19 to .23 thatthe holes in drum 20 are substantially larger than the diameter of thepins, so that these pins can start entering the holes which theyencounter quite early, without striking the edges. Furthermore, itshould be noted that the marking holes 29 are inclined at an angle tothe drum radius, while the spacing holes 28 extend substantiallyinradial direction. This is necessary, because the marking pin m isinclined in the direction of the drum rotation, while spacing pin s isinclined more or less against the drum rotation. 1n order that each pinshould encounter the hole Wall first near the hole bottomfso as to staycontact with the wall as long as possible in order to tilt frames Li9and 50 at the largest possible angle, the holes 29 must hey inclined asdescribed. T his Willbe obvious especially clearly from Figs. 19 to 22.Vi When the rocking of frame Al() continues clockwise, spacing pins ispushed gradually to the bottom ofthe spacing hole 28 which it-hasentered in Fig. l0, and when this happens (as showin in Fig. l1) pin sis taken along drum 29V in vthe direction of the arrow and tilted to theleft back into thel position shown in Fig. S. By kthis tilting frame 50of pin s, together with contact lever 5 5 is rocked counter clockwise sothat the contact lever is thrown from the marking contact M back tothespacing contact lS as shown in Fig.` .8. Through the interlinkingbetween levers 55 and 54, the latter lever-is rocked clockwise, andthereby rocks the guideframe 49 of marking pin m (which latter inthemeantime has been withdrawnfrom its hole) to 'theiright into the spacingposition shown in Fig. 8, in which it is readyto Ameet the next markinghole 29 as shown in Fig. 8.* From the position of the pin slots 61, 62inthe tapebridge shown in plan in Fig. 5, it will be observed that thetilting range of spacing pin s is set slightly beyond the tilting rangeyfor the marking pin m in the direction of the `selector drum rotation.This is arranged so that when a marking contact is made as in Fig.llhfor instance due to the `first marking perforation c in Fig. 24, andimmediately thereafter a spacing contact should occur, in order toproduce a short code dot, as shown by the first hole Zin Fig. 24, thespacing pin s is in a position to enter this first perforation d, i.

land the corresponding hole 2S in drum 20 as shown in Fig. `l0, so as topromptly `throw the contact lever onto the spacing contact. n From thesemovements so far described it will, therefore, be clearly seen that thefunction of rocking frame 42 is to advance the pins m and s into,respectively out of engagement with selector drum 20 without any effectupon the .contactposition of arm 55,

whereas the function of drum QO-is to posi- 15"' tively tilt the `frames49 and 50 toward or away from one another, and to thereby directlyaffeetthe position of contactarm 55 with respect to contacts M and S. i l

Since the engagement of drum 20 by the pins depends upon the presence ofa perforation in the tape, it follows that the position of contact arm55 with respect to the marking and spacing contacts M and -S is directlycontrolled by the presence or absence of-V perfforations in the tape inFig. A24. For instance, in Fig. 22 in which the spacing pin s' is shownin a marking hole 28 c-f drum 2O (see also Fig. 11) ready to be carriedby drum to the left in order to throw contact lever 55 from the markingcontact M in Fig. 11

` onto the spacing contact in Fig. 8, this throwing of the contact armcannot occur in the case, witha similar position of frames 49 and V,land a similar tilting of pins 8 and m,

fshbwn in Fig. 23, Where the tape has no perf'ortion, so that thespacing hole 28 in the igiire, which-is inthe same position of spac-"ing' hole 28 of Fig. 22, is coveredby the tape. In that case, insteadof advancing into hole 2 8 when its'frame 50 advances, pin sis pushedback into the frame, as shownin that figure, against the tension of itsspring 65. Drum 20 now continuing to rotate in the direction of thearrow, hole 28 passes by the tip of pin -s without having tilted frameY5() and, therefore, without having thrown contact arm from the markingto the yspacing contact. This missing of holes continues until a spacingperforationV arrives through which pin s can enter into a spacing hole28 such as is shown in Fig. 22. This condition vice versa prevails whenthe contact arm happens vto standen ay spacing contact brought about-tion of the arrow shown in that figure, neither the spacing or markingpin can enter into the next hole 28, respectively 29, of drum 20, andthe contact arm remains in spacing position as shown in Figs. 8 and 9.Thus, in Fig. 24 the tape space'between b1 and a2 i passes over drum 20.This produces inthe receiver a directiony of currentlow in accordancewith which the recorder pen p in Fig. 25 remains in its lowermostposition, and thereby produces the line b1 on this tape which is aspacing line between signals. As soon as the vtirst marking hole a 2 inFig. 24 arrives within the range of the marking pin an, this pin willenter the hole as in Figs. 8 and-9, and will be taken along by the drumtothe left and throw contact arm 55 from the spacing contact onto themarking contact. Since in Fig. 24 no spacing perforation occurs directlyunderneath the first marking hole a2, the corresponding spacing hole 28in drum 2O remains covered, and thus the contact arm remains on themarking contact and produces the first line a2 on the receiving tapeFig. 25. Upon arrival-of the first spacing hole b2 in Fig. 24 the devicethrows the contact arm onto the spacing contact and produces the firstspacing line :b2 in Fig-25, and

so on. For instance atv c in Fig. 24 a spacing hole d is right in linewith a marking hole c and, therefore, the contact arm 55 will be thrownimmediately, after having arrived on' the marking contact, back to thespacing contact and back to the marking and back to the spacingycontact, thereby producing two short dashes 0 with the short interveningspace in Fig. 25. y

It should be particularly noted with relspect to the'function ot thecontact arm that this arm is not only positively moved between themarking and spacing contacts in,r

accordance with the dictationy of the perforation in the tape, due tothe positive action of drum 20 on the marking andvspacing pins, by whichalone the tilting of the two sliding frames 49 and 50 can occur, but themovement of this contact arm, when it does 1 occur, always occurs inabsolutely timed relation with the rotation of drum 20. Since this drumis positively geared to the star wheel roller which positively feeds thetape .p as'previously described, and since it is likewise positivelygeared to the longitudinal motions of the two sliding frames 49 and 50,the making and the breaking of the contact at M andS is positively andwithgreat eX- natural Vibrations or lags of operating elements, such assprings which are used in the prior art type keying heads, can occur.

The contact mechanism for the marking and spacing contacts M and S ofwhich in Figs. 8 to 11 only'fragments are shown, is

constructed as follows.v Referring to' Fig.

2 the contact arm 55 which protrudes beyond the left side of the leverbox 12, is surrounded at its outer end bythe contact box 13, the coverof which ispartly broken away in Fig. 2. This box consists of a baseplate of insulating material on which are mounted two metal contactblocks 71 and 72 to which the leads 73 and 74 respectively areconnected. These leads are connected to contact pins at the rear of thekeying head casing 10 (see Figs. 3 and 4) at which point the leads areconnected into the transmitter wiring system such as is showndiagrammatically in Fig. 16. Contact blocks 71 and 72 each carry anadjustable contact screw 75, 7 6 respectively, which is provided with acontact point M and S, respectively', representing the marking andspacing contacts. After the proper spacing adjustment of screws 75 and76 with relation to the contact arm has been made, these contact screwsare set by means of the clamping screws 77, 78. One of the contactblocks is shown in considerably enlarged horizontal section in Fig. 12.Since as previously de cribed the contact arm 55 lli- Vwhich is heldinthe position shown by means of a. comparatively strong spring 7 9which is positioned in the hollow screw by means of a `plug 8O threadedinto the outer end of screw v76.

In order to retain the Contact arm on the Contact on which 1t has been,thrown by the mechanism, and until it is positively removed by themechanism from this contact, a toggle joint is provided which Aengagesthe outer end of contact arm 55 as shown in Figs. 2 and 2a. This togglejoint consists of an X-shaped toggle block 81 which engages the edgedend of the contact arm at the bottom of one of its grooves as shown indetail in Fig. 2a, the

i .n bottom of the opposite groove of this toggle blockV being engagedby the edged pawl 82 forming the head of a fiat spring 83 mounted on themain casing at 811. The edge of pawl 82 is placed exactly in horizontalalignment with the edged end of -arm when it stands inthe middleposition between the two contacts, so that when the arm is thrown ontoone or the yother contact, toggle block will snap over the edged end ofarm 55 to one or the other side, the pressure of spring 83 eX- .ment ofthis block.

erted through pawl 82 holding it there with a certain amount of force,until it is positively removed by the operating mechanism. In order toprevent the toggle block 81 from jumping out of position at high speedoperation, pa-wl 82 is provided with a. central vertical slot 85 shownin Fig. 2a through which passes a small pin 86 driven into the toggleblock 81. This prevents lateral move- In order to avoid an undueexertion of pressure by spring 83 against-arm 55 and thus against thepivotal bearingk of arm 55, this toggle joint may be arranged as shownin Figs. 2b and 2c. In this case leaf spring 83 is replaced by a lever123 pivotally attached at its lower end to a foot 125 mounted on block84 mentioned before. Pawl 82 is provided at the other, free end of thislever and eng-ages one side oftoggle block 81,Kwhose other side engagesarm 55, the same as in F ig. 2a. In Figs. 2b, 2, however, the springpressure is exerted diderently. Arm 55 is provided with a transverse pin12 and pawl 82 with a transverse pin 122, Between the ends of thesepins, on each side of the toggle block, is provided a tension spring121, which Spring pulls pawl 82 toward the end of arm 55 with the toggleblock between. The effect is similar to that described with reference toFig. 2a, provided the edge of pawl y82 is properly placed with respecttothe edge of the armend when the arm is in middle posiL tion. In thiscase, however, the spring pressure affects only the pawl andthe arm end"i and the toggle block without pressure being exerted against thepivotal bearing of'arm 55.

In order to reduce as much as possible the y mass of all elements movingat highspeed they are perforated wherever feasible. For

instance, contact arm 55 asv shown in Fig. Y

15 is provided with a number of transverse perforations 88, and the twopin guide frames L19 and 50 are provided near the upper end withtransverse perforations 89. y

The entire lever gearing contained inbox 12 is constantly splashed withoil, and for this purpose the casing is partly filled with oil as shownat 90 in Fig. 2. In order that the oil may not creep out through theside of box 12 through which the contact arm 55pmtrudes, this arm runsthrough a splash box 91 which is inserted in the side Wallof 4boxy 12and which extends partly into the` boxes shown for instance in Figs. 7and 8. In case oil shouldysplash onto arm 55 insideof the box and tendto run along the arm toward the outside, it must first run intosplashboav 91 in which the small drops of oil are readily shaken ofi'bythe rapid oscillations .of arm 55, and they collect at the bottom ofthe box, whence the cil is drained through hole 92 shown in Fig. 7 backinto box 12.

The cover 93 of the lever boX 12 serves at the same time as a supportfor the pivot pins and shafts extending transversely through this box asshownindetail in Figs. 7 and 8. For instance, main pivotal shaft 40, 41,3,8 in

ig. 6 has its outer supportinglmshingY .39 mounted in the box cover 93,this bushing extending sufciently far into the boX to lfold rockingframe 4:2 laterally in place on its pivot. Further, spacing elements 941and 95 are fastened on cover 93 which serve for supporting the free endsof pivot studs 56 which carry the Contact arm 55 and the interlinliinglever 54. These spacing elements 94, 95 are each of sufficient length toextend respectiveJlh ly to the contact arm and to the interlinking leverto hold these elements laterally in place on their pivotal aXes.-

It has been stated at the beginning with reference to the description ofthe tape drive mechanism shown in F igs. 2. 3, 1.11, 17. and v18 Y V31and 32 apart to remove the stal' wheel roller 23 sufficiently from drum20`to insert the perforated tape 26, and toproperly bring its centralperforations in engagement with the pin teeth of the star wheel, thetape releasebar 101 is provided. This vertical bar is slidingly insertedinto and flush with the Vrear wall of box 12 and is provided at itsupper end with a roller 102 (shown in large scale in Fig. 6) whichstands in alignment with the ends of arms 31 and 32 which ends, when thetape drive gear is in mesh, surround roller 102 at the bottom. When bar101 is pulled down the lower ends of arms 31 and 32 are spread apart asshown in Fig. 18 by which the star wheel gear 22 is thrown fouty ofengagement with the driving gear 21 of drum 20, and the star wheel 23and tape guide roller (Fig. 14) are sufficiently far removed from drum20 to permit the insertion of the tape from the front of the keyingvvdevice in Fig. 2. The number of pin teeth on star wheel roller 23(Fig. 14) is equal to the number of gear teeth of the roller gear 22,and both are axially in alignment. Likewise, the number of marking andspacing holes on drum 20 is equal to the number of gear teeth of gear21, and the holes and the teeth are in axial alignment. Thus, when theperforated tape is inserted so that the teeth 24 of the star wheelproperly enter the central perforations f of the tape (Fig. 24) theouter rows of perforations' of the tape for marking and spacing willalways exactly register with the respective marking and spacing holes ondrum 20, as soon as the gears are put back into mesh.

From the previous description of the mechanism, by which the marking andspacing pins are caused to penetrate through the perforations in thetape, it will be noted that at all operating positions of theV pinmechanism at least one of the pins is penetrating a perforation, or ifthe tape has no perforation there is at least one pin sufficientlytensioned by its spring so that it would penetrate through the tape if ahole were present. It would, therefore, be impossible, notwithstandingthe releasing mechanism for the tape drive previously described,l toinsert a tape into the lmechanism or withdraw it therefrom. In order toclear the drum and the tape entirely of the marking and spacing pins`when the tape is to be withdrawn or i inserted the following mechanismis provided.

It had been mentioned at the beginning with reference to the descriptionof the pivotal shaft 38. which carries the eccentric 41 (Fig. 6) onwhich the rocking frame 42 rocks.y

that this shaft is mounted at 40 in the rear wall of the casing. itsthinner end 38 protruding through the front of the casing. So long asthe eccentric 41 stands in the position shown for instance in Fig. 8,the vertical operating range of sliding frames 49 and 50` extends farenough upwardly, so as to allow the marking and spacing pins topenetrate into the respective holes of drum 20, Vand to function in themanner described herinbefore. If, however, as shown in Fig. 16 shaft B8is revolved 180, he eccentric isthrown into its lowermost position, andthe vertical operating range of the two guide frames '49 and 50 islowered suliciently, so that even in the furthest upward position pins sand m remain below the surface of tape bridge 60. Thus, the path forinserting or removing the tape is entirely cleared. In order to throwthe tape drive gear into and out of mesh, together with the lowering ofthe operating range of the spacing and marking pins below the surface ofthe tape bridge 60 as just described, a pintle 105 is attached to therear end of pivotal lshaft 40 which engages a slot 106`providedin theenlarged lower end of sliding bar 101 previously described withreference to Figs. 6, 17 and 18. I/Vhen pintle 105 is elevated, shaft 40stands in the position with eccentric 41 raised, and the tape drivegears are inv mesh, and the entire keying operating mechanism isinoperating position as shown in Figs.'8 to 11. As soon as pins s and mare drawn below the surface of tapebridge 60 by throwing eccentric 41180o down, pintle 105 throwsbar 101 into the position shown in Fig.18 inwhich the tape drive gears are released. For operating pivotal shaft 40,41, 38 in this manner an operating handle 107 (Figs. 2 and 6) isattached to the protruding end of shaft 38, whichV handle is locked bymeans of a spring controlled pin 108 in its uppermost position shown inthese figures, which is the operating position of the device with allgears in mesh. lVhen handle 106 is withdrawn against the pressure ofspring 109, pin 107 isdrawn out of its socket and the handle can beswung 180 and the lever be locked in the lower socket 110 in whichposition the mechanism is cleared for insertion of the tape.-

We claim:

1. In an automatic keying head in combination av movable Contact arm, apositively driven arm operating element, a coupling device adapted topositively 'couple said arm with said operating element, and a tapeperforated to represent the signals tobe keyed, and being interposedbetween said operating element and said coupling device for preventingthe arm coupling by said device, except through a perforation in saidtape.

2. In an automatic keying head in combination a movable contact arm, aconstantly, positively driven arm operating element, a coupling deviceadapted to positively couple said arm with said operating element, and atape perforated to represent the signals to he keyed, and beinginterposed between said operating element and said coupling device forpreventing the arm coupling by said device, except through a perforationin said tape. i if 3. In an automatic keying head in combination amovable contact arm, a constantly, positively driven arm operatingelement, a coupling device adapted to intermittently positively couplesaidarm with said operat-` ment and said coupling device for preventingthe arm coupling by said device, except through a perforation in saidtape.

5. In an automatic keying head in combination a movable contact arm, aconstantly, positively driven arm operating element, an oscillatingcoupling device, positively driven in timed relation to said operatingelement, and disposed to intermittently positively couple said arm withsaid operating element, and a tape perforated to represent the signalsto be keyed, and being interposed between said operating element andsaid coupling device for preventing the arm coupling by said device,except through a perforation in said tape.

6. In an automatic keying head in combination, a movable contact armoperably disposed between two abutment contacts, a positively driven armoperating device having means geared to it for positively conveying withsaid device a tape, perforated to represent the signals to be keyed, andcoupling means, positively geared with said arm and adapted to engagesaid arm operating device, for positively moving said arm in eitherdirection between said contacts, said tape being interposed between saidoperating device and said couplin@f means to prevent the engagement ofsaid coupling means, except through a perforation in said tape.

7 In an automatic keying head in combination, a movable contact armoperably disposed between two abutment contacts, a positively driven armoperating device having means geared to it for positively conveying withsaid device a. tape, perforated to represent the signals to be keyed,and coupling means, positively geared with said arm and disposed andoperated in timed relation to.

the motion of said operating device, toengage said arm operating deviceat uniform intervals to cause the positive movement of said armalternately from one contact tothe other, said tape being interposedbetween said operating device and said coupling means to prevent theengagement by said cou-r,

pling means, exceptthrough a perforation in said tape.

8. In an automatic keying head in combination, a movable contact armoperably disposed between two abutment contacts, a positively driven armoperating deviceA having means geared to it for positively conveyingwith said device a tape perforated .to represent the signals to bekeyed, and coupling means, positively geared to said arm and includingtwo coupling elements disposed and operable in timed relation to themotion of said operating device to alternately engage said arm operatingdevice ,at uniform-intervals to cause the positive movement of said armalternately from one contact to the other, saidtape being interposedbetween said operating device and said coupling means to prevent saidelements from engaging said device, except through a perforation in saidtape. t 9. In an automatic keying head in combination a pivoted contactarm disposed between two abutment contact-s, a selector drum positivelydriven at uniform speed, and means geared to said drum for positivelyconveying in timed relation to the drum motion a ytape perforated torepresent the, signals to be keyed, a coupling devicepositivelyconnected to said contact arm and including ytwo re-v ciprocatingcoupling pins, operable in timed relation to the drum motion, anddisposed to. alternately move toward'and away from said drum, said pinsbeing spaced apart in the` direction of the drum axis, said drum havingtwo peripheral rows of suitably spaced holes, one row for each pin,whereby said pins are permitted to alternately` enter a hole of each rowto couple the arm with said drum to cause the positive movement of thearm by the drum movement from one Contact to the other during suchcoupling engagement, said tape being interposed between said drinn andsaid pins to prevent said pins from entering said drum holes, exceptwhen cleared by a perforation in the tape.

l0.. In an automatic keying head in combination a pivotal contact armdisposed betweentwo abutment contacts, a selector drum positively drivenat uniformk speed, and means geared to said drum for positivelyconveying in timed relation to the drum motion Aa tape perforated torepresent the signals to be keyed, a coupling device comprising aninterlinking pivoted arm coupled at one endin'g two peripheral rows ofsuitably spaced holes, one row for each'pin, whereby said pins duringthe :trame reciprocation can alternate'ly enter' a hole of each row topositively f intermittently couple said contact arni with said drum tocause the positive movement of said arm by the drum' motion alternatelyfrom one contactto theV other duri-ng such coupling engagement, saidtape being inter- :posed between said drum and said pins to y arm, twosliding Jframes one disposed on each of said arms and spaced apart onefrom the other in the direction of the selectorv drum axis, areciprocating device geared in timed relation to the drum motion andconnected to' said frames to` alternately moveY said fram es toward andaway from said drum, a coupling` pin yieldingly disposed at the end ofeach frame, said drum having two peripheral rows of suitably spacedholes, one row for eachpin,A whereby said pins during the framerecipro'cation can alternately enter a hole of each row to positivelyintermittently couple said contact arm with said drum to cause thepositive movement of said arm. bythe drum motion alternately from onecontact to the otherv 'during such coupling engagement, said tape beinginterposed between said drum and' said pins, to prevent said pins fromentering said drum holes except when cleared by :i

. perforation in the tape, said pins yieldingly receding into theirrespective frame when prevented by the tape from entering a drum hole.

12. In an automatickeying head in comu bination a pivot-ed Contact armdisposed between two abutment contacts, a selector drum positivelydriven at uniform speed, and means geared to said drum for positivelyconveying in timed relation to the drum motion 'a tape perforated torepresent the signals to be keyed, a eouping device comprising aninterlinking pivoted arm coupled at one end with the rear end of saidContact arm,

so that both arms rock in oppositev directions, a sliding block fixed oneach arm and a sliding frame on each block disposed to slide toward andaway from said drum, a reciprocating device geared intimed. relation tothe drum. motion and connected-'to said frames to alternately move theframes. toward Vand away from the drum,qa 'coupling` element at the endof each ltraine adapted to engage said drum during the framereciprocation l to couple said contact arm with said drum during suchengagement for positively moving said arm by the drum motion alternatelyfrom one contact to the other, said tape being interposed between saidcoupling elements and sai-"d drum to prevent said elements trom.

engaging said drum, except through a perforation in said tape.

13. In an automatic keying head iii combination a pivoted contact armvdisposed between two abutment contacts, a selector druml positively'driven at uniform speed, and

means geared to said drinn for positively con'-A veying in timedrelation to the drum motion a tape` perforated to represent the signalsto be keyed, a coupling device comprising an interlinking pivoted armcoupled at one end with the' rear end of said contact arm, so that botharms rock inopposite' directions, a sliding block fixed on each arm anda slidi-ng frame on each block disposed to slide toward and away fromsaid drum,a reciprocating device gearedin timed relation to the drummotion and connected to said frames to alternately move' the framestoward and away' from the drum, said frames being spaced apart in vthedirection of the drum axis, a vieldingly disposed coupling pin arrangedin the endV of each frame, said drum haviiiga pel rip'heial row of holesfor each pin, spaced apart in each row the shortest distancebe-` tweenadjacent holes occurring in the tape,

whereby said pins can alternately enter ahole of each row during' theframe reciprocation to intermittently positivelycou-ple said contact arm'with said druni toy cause the positive rocking of said arm through thepins by the drum motion alternately from one Contact tov the otherduring suoli coupling engagement, said tape being. interposed betweensaid. drum and said pins to prevent sind pins from entering said drumholes, except when cleared by a perforation in the tape.

14t- In an automatic keying head 'in combination a Vpivoted contact armdisposed be-A tween two abutment contacts, a selector drum positivelydriven atuniform speed,and`means geared to said drum for positivelyconveying in time-d relation tothe drum motion a tape perforated torepresent the signals to be' keyed, aV coupling device comprising aninterlinkingy pivoted arm coupled at one end with the rear end of saidcontact arm, so that both arms rock in opposite directions, a slidingblock fixed on each arm and a sliding frame on each block disposed toslide toward 'and' away from' said drum, a reciprocating device gearedin timed relation to the drum motionl and connected to'l said frames toalternat'ely movethe'frames toward and away from the" drum, said framesbeing spaced apart in the direction of the drum anis, a yieldinglydisposed coupling pin arranged'iii the end of't each frame, said drumhaving a peripheral row of holes for each pin, spaced apart in each rowthe shortest distance between adj acent holes voccurring in the tape,said frames and pins being inclined towards one another at their ends,the drum holes for Vthe pin, whichA is inclined towards the direction ofdrum rotation, being inclined toward that direction, the holes'for thepin, which is 'iiiclined against the drum rotation extendingsubstantially in .radial direction, whereby each of said pins canalternately with the other freely pass into an encountered hole of its'row to the hole bott-oni during the frame. reciprocation, to be takenalong by the hole Wall, and to thereby7 positively rocikv said contactarm through the drum motion from one contact to the other, said tapebeing interposed between said drum and said pins to prevent said pinsfrom entering said drum holes. except when cleared by a perforation inthe tape.

15. In a lever systeni, pivotally mounted to Y oscillate between twoabutments, a toggle element supported at one of its points at a point ofsaid system which partakes in the oscillation, and a yielding elementdisposedto support said toggle element at another point and to exert apressure against said element toward its othersupporting point in thedirection of a line extending between said supporting points when thesystem is positioned intermediate its abutments, whereby said toggleelement is held between its supports in -an unstable equilibrium,tending to throw and hold said system either against one or the other ofsaid abutments.

16. In a lever system a lever arm, pivotally mounted to oscillatebetween two abutments,

a toggle element supported at one of its points at the end of said arm,and a spring pressed pawl having its end disposed to support said toggleelement at another point and to exert a pressure against said elementtoward its other supporting point in the direction of a line extendingbetween said supporting points when the arm is positioned intermediateits abutments, whereby said toggle element is held between its supportsin an unstable equilibrium, tending to throw and hold said arm eitheragainst one or the other of said abutments.

17. A keying head having oppositely disposed abutment contacts, aContact arm, and means for moving said arm alternately onto saidcontacts at suitable intervals, and means for holding said arm on eithercontact during said intervals, comprising a pawl provided with an edgedhead and having the edge disposed opposite to and in line with thesimilarly edged end of the arm, when the arm is in a positionintermediate said contacts, a toggle block grooved on opposite sides andinterposed at its grooved portions between said two edges, a springdisposed to to said contacts atsuitable intervals, and

means for holding said arm on either conn tact during said intervals,comprising a pawl l provided with an edged head and havingthe edgedisposed opposite to andin line withv the'similarly edged e-nd ofthearm, when the arm is ina position intermediate said contacts, atoggle block grooved on opposite sides and interposed at its groovedportions between said two edges, a spring disposed -to press said pawland toggle block toward the" arm end, whereby said block is held in anun-A stable equilibrium between the two edges and, through the springpressure, tends to hold the arm on the contact, against which it hasbeen thrown by said moving means, and means for holding said blockm ofsaid edges. i l

19. In an automatic keying head in 'combination, a movable contact armoperably dis-V posed between two abutment contacts, a positively drivenyarm operating device havingv means geared to it for positively conveyingwith said device a tape, perforated to represent the signals to bekeyed, and couplingV means, positively geared withsaid arm and adaptedto engage said arm operating device, for positively moving said arm ineither di-' rection between said contacts,said tape being interposedbetween said operating device and said coupling means to prevent theengagef` ment of saidl coupling means, except through av perforation insaid tape,'each of said abutment contacts having al cushioned contact'point to prevent the rebound of said contact arm. l v j 20. In anautomatic keying head in combination two abutment contacts and apivotedContact arm disposed and movable therebetween, a selector drum having apluralityof recesses on its periphery and being Vpositively driven atuniform speed, a tape'feed' positively geared to said drum and adaptedto convey over rsaid drum a tape perforated to represent the signals vtobe keyed, a reciprocating coupling device connected'with said arm andhaving coupling pins adapted to alternately engage the drum recessesthroughtlie tape perforations for coupling the arm intermittently withsaid drum toy movethe arm from one contact to theother in' accord ancewiththe occurrence of the tape perforations, and a rotatable pivotalshaft havingan eccentric serving as a pivot for said-rel ciprocatingcoupling-whereby through the rotation ofthe eccentric said reciprocatingposition longitudinally coupling may be raised and lowered to move saidpins into and out of operating range with said drum recesses, means forhand operating said pivotal shaft, and means operatively connected withsaid pivotal shaft for simultaneously removing said tape feed from saiddrum to clear said drum for insertion and removal of the perforatedtape. l

21. In a keying head of the character described, in combination acontacting mechanism, a rotating selector drum, a coupling mechanismbetween said drum and said contactingmechanism for putting thecontacting mechanism under the .control of saidfdrum, and a tape drivefor feeding a perforated tape over the peripheryV of said drum tocontrol said coupling through the tape perforations, said tape drivecomprising two pivoted arms, disposed with their ends adjacent to saiddrum and on opposite sides of the drum axis, one arm carrying near itsend'a tape drive roller and its driving pinion, the other arm carryingnear its end a tape guide roller, a gear wheel on said drum engageablewith said roller drive pinion to feed said tape positively and in timedrelation with the drum speed over said drum, means for normally forcingthe free arm ends towards one another to hold said tape feed roller andsaid guide roller in engagement with said drum, and hand controlledmeans for spreading said arms apart to clear said drum from the tapefeed and from the guide roller to permit the insertion and the removalof the tape.

22. In aleying head of the character described, in combination acontacting mechanism, a rotating selector drum, a coupling mechanismbetween said drumfand said contacting mechanism for putting thecontacting mechanism under the control of said drum, and. a tape drivefor feeding a perfo-V rated tape over the periphery of said drum tocontrol said coupling through the tape perforations, said tape drivecomprising two pivoted arms, disposed with their ends adjacent to saiddrum and on opposite sides of the drum' axis,- one arm carrying near itsend a tape drive roller and its drivingpinion, the other arm carryingnear its end a tape guide roller, a gear wheel on said drum engageablewith said roller drive pinion to feed said tape positively and in timedrelation with the drum speed over said drum, a tension spring Y for'normally forcing the free arm ends -towards one another to hold saidtape feed roller and said guide roller in engagement with said drum, anda Cam roller disposed midway above said arm ends, and hand controlled.means for moving said cam roller against said cam ends to spread thearms apart to clear said drum from the tape feed and from the guideroller to permit the insertion and removal of thetape.

23. Inv a. keying head ofthe character described, in combination acontacting mechanism, a rotatingy selector 'drum, a vcmlpliiig mechanismbetweensaid drum and saidcontacting mechanism for putting tirecontacting mechanism under the control of ysaid drum, and a tape drivefor feeding al perforated tape over the periphery of said drum tocontrol saidY coupling throughV the tape perforations, said tape drivecomprising two pivoted arms, disposed with'their'endsadjacent to saiddrum and on opposite sides of the drum axis, one arm 'carrying near itsend a tape drive roller and .its driving pinion, the other arm carryingnear its end a tapeguide roller, a gear wheel on said drum `engageablewith said roller drive pinion to-feed said tape positively and in timedrelation with the drum speedl over' said drum, means for normallyforcing the free arm endsvtowards one another to hold said tape feed'roller and said guide roller-in engagement with said drum, andhandcontrolled means for spreading said arms apart to clear said' drumfromthe tape' feed and from the guide roller to permit the insertion andthe removal of the tape, and means operated by the same hand control-ledmeans for simultaneously removing said coupling mechanism' outnofcoupling range with said drum to clear the drum also from said couplingmechanism for the insertion and removal of the tape.

Y FRANK KUNG. .ERNEST KNOPP.

